The present invention relates to hue control of a composite color video signal, and more particularly to digital hue control without chrominance demodulation for PAL television by using a polyphase interpolator to change the phase of the color difference signals.
In the PAL television standard, one of the commonly used broadcast television standards used throughout the world, color information is represented by the phase of quadrature modulated color difference signals, U and V. Traditionally, because of the alternation of sign of one of these components, V, from line to line, phase changes, or color or hue changes, are accomplished by demodulating the chrominance information of the composite PAL signal, changing the color difference signals, and then remodulating the new color difference signals. To achieve the chrominance information demodulation the composite PAL signal is decoded into luminarice Y and modulated color C signals. Demodulating and remodulating the chrominance signal adds additional circuitry with its attendant space and expense costs.
What is desired is a hue control method without chrominance demodulation.